1. Field of the Invention
This invention relates to a sheet feeding device for feeding sheets by sheet feeding means having a sheet feeding roller, and an image forming apparatus provided with the sheet feeding device, and particularly to a structure for effecting the cleaning of the sheet feeding roller of the sheet feeding device.
2. Description of the Related Art
Heretofore, in a sheet feeding device for feeding sheets by sheet feeding means having a sheet feeding roller, there has been one provided with a brush member as cleaning means for cleaning the sheet feeding roller, and this brush member, as described in Japanese Laid-Open Patent Application No. 53-106130 or Japanese Laid-Open Utility Model Application No. 57-37942, is disposed in such a manner as to always contact with the sheet feeding roller.
FIG. 19 of the accompanying drawings shows the construction of a sheet feeding device having such a brush member mounted thereon, and in FIG. 19, the reference numeral 200 designates a sheet feeding roller. This sheet feeding roller 200 is provided with sheet feeding roller rubber 205 forming the surface of the roller and having a high coefficient of friction, a sheet feeding roller collar 206 fixing the sheet feeding roller rubber 205 and held by a sheet feeding shaft 207 suitably rotated by drive means and control means, not shown, a sheet feeding roller 208 for depressing the upper surface of a sheet bundle S at first, and an idler roller 209 for spacing a sheet apart from the sheet feeding roller 200 while after the sheet feeding operation, the trailing end of a sheet conveyed by a conveying device or the like, not shown, remains in a sheet supply tray 201, and being rotatable to thereby minimize the resistance force received by the sheet.
On the other hand, in FIG. 19, the reference numeral 217 denotes a roller cleaning brush which is cleaning means, and design is made such that this roller cleaning brush 217 removes paper powder resulting from the sheets formed of a fibrous material, a filler or the like which adheres to the surface of the sheet feeding roller rubber 205. The reference numeral 218 designates a brush holder for holding the roller cleaning brush 217, and this brush holder 218 is mounted on the frame member 219 of an image forming apparatus provided with the sheet feeding device.
Design is made such that by the paper powder formed of fibers or a filler which thus adheres to the surface of the sheet feeding roller rubber 205 being scraped off by the roller cleaning brush 217, the frictional force of the sheet feeding roller rubber 205 which is necessary for sheet feeding can be maintained for a certain degree of period.
In such a prior-art sheet feeding device, however, when such paper from the surface of which fibrous paper powder is simply stripped off is fed, a great deal of paper powder adheres to the surface of the roller rubber. When a great deal of paper powder adheres to the surface of the roller rubber, this paper powder comes to accumulate on the brush because, as already described, the roller cleaning brush 217 is designed to always contact with the sheet feeding roller 200 in its fixed state.
When the paper powder thus accumulates on the brush, there has been the problem that the cleaning effect is lost and bad sheet feeding occurs.
Also, in the case of an image forming apparatus of a construction in which for example, a sheet feeding device is disposed in the lower portion, a sheet feeding roller is disposed in the inner part of the bottom of the image forming apparatus, and a roller cleaning brush for cleaning the sheet feeding roller is disposed at a location more difficult of access by a hand. This has led to the problem that the interchange of the sheet feeding roller and the roller cleaning brush is troublesome.